This application is the national phase under 35 U.S.C. xc2xa7371 of PCT International Application No. PCT/KR99/00664 which has an International filing date of Nov. 5, 1999, which designated the United States of America.
The present invention relates to a modified polystyrene spherical resin and a process for decontaminating waste water by using the modified polystyrene spherical resin. More particularly, the present invention directed to a process for decontaminating process by using polystyrene spherical resin grafted with polyethylene glycol as a adsorbent, and a process for elutriate an adsorbent from the adsorbent adsorbing contaminant through a simple process to resuscitate the adsorbent.
Industrial waste water is a malignant water pollutants. For example, waste water of dye industry, heavy metal ion contained in waste water, surfactant, humic substance contained in trash sediment cause serious environmental problems. Up to now, several methods for treating such malignant pollutants have been suggested, that is, chemical, physical and biological treating process are known to a public.
Among such methods, chemical treatment processes employ chemical unit processes, for example, oxidation process which decomposes chromophore of dye by using oxidation agent and thereby decolourizes waste water. Hydrogen peroxide, etc., are used in this oxidation process [Yamasaki, K.; Sakata, K.; Yokotani, A; Japanese Patent Appln. No. 10-080,693(1998): Hirotsuji, J.; Kaai, Y.; Ikeda, A.; Japanese Patent Appln. No. 08-267,077(1996): Taoda, H. Japanese Patent Appln. No.05-253,581(1993): Saito, S.; Murayama, K.; Misawa, K. Japanese Patent Appln. No. 03-188,992(1991): Mizutani, K.; Inoue, H. JP 51,144,060(1976)]. Recently, O3, etc., are reported as a new oxidation agent. [Kataoka, K. Japanese Patent Laid-Open Publication No.10-137,780(1998): Ueno, S. Japanese Patent Laid-Open Publication No. 10-151,471(1998): watanabe, M.; Hayashi, F.; Dazai, K. Japanese Patent Laid-Open Publication No. 10-165,757(1998): Hayashi, F.; Watanabe, M.; Nishino, Y.; Dazai, H. Japanese Patent Appln. No.10-118, 144(1998): fischer, W. G. European Patent Publication No. 822, 271 (1998)].
The oxidation process decolourizes waste water, however, may creates toxic by-products which remains in waste water, and thereby cannot lower the COD value. In addition, when O3 or electron beam is used as an oxidant, energy consumption is enormous.
The biological process, in general, employs micro-organism in aeration tank. However, this method requires spacious plant site, long process time, intricate conditions and operation for activation of microorganism.
Meanwhile, the physical process employs active carbon adsorption method. [Nikolaevsky, R.; Monosov, M.; Monosov, E.; Sharony, E.; Gurevich, D. U.S. Pat. No. 5,792,336(1998): Maesaki, M.; Nakajima, M.; Hasegawa, H. Japanese Patent Appln. No.09-253,669(1997): Matsumoto, Y.; Sugano, N.; Inui, T.; Akao, K. Japanese Patent Appln. No.09-248,562: Hatano, Y.;. Shirama, S.; Ishikawa, T.; Yobiko, Y.; Takaoka, S. Japanese Patent Appln. No. 08-281,271(1996): Sugiura, W.; Tanaka, S.; Shimotomai, K. Japanese Patent Appln. No. 08-000,261(1996): Tamatoshi,K.; Morishima, K. Japanese Patent Appln. No. 07-047359(1995): McCollam, F. M. J. British Patent Appln. No.2,280,430(1995): Michna, M. ; Puppe, L. German Patent Appln. No. 4,213,163(1993)]
However, these physical processes have also some demerits. That is, active carbon which has been used in adsorption process, cannot be regenerated, and therefore, should be destructed by incineration. The incineration process employs bunker-C oil, which leads to energy consumption and air contamination.
Therefore, in order to overcome the above described drawbacks of the prior arts, the inventors of the present invention have conducted an extensive research for many years for developing polystyrene adsorbent which can be used repeatedly in waste water treatment process.
Finally, the present inventors have prepared a novel polystyrene adsorbent and a novel waste water treatment process which, can substitute entirely traditional active carbon process and which can save utility expense for waste water treatment remarkably.
The preparation methods of the adsorbent of the present invention are described in detail in present inventor""s U.S. Pat. No. 5,466,758(1995), Korean Patent No. 119,262 (1997), Korean Patent No. 119,263(1997) and Korean Patent Appln. No. 98-47748.
It is therefore objects of the present invention to provide a novel adsorbent resin which can be used in novel processes which can substitute entirely traditional granular active carbon adsorption method for waste water treatment.
The capacity of adsorption of the polystyrene resin grafted with polyethylene glycol of the present invention can be controlled by adjusting the content and molecular weight of polyethylene glycol. Also, the adsorption efficiency of the adsorbent of the present invention are varied depends on grafting method.
The present inventors have widely researched the cross linking ratio and size of the polystyrene spherical resin which can be used repeatedly in adsorption/desorption/regeneration processes without loss of physical and mechanical properties thereof.
As a result, the present inventor discovered that the polystyrene spherical resin which is crosslinked with 1 to 10 wt %, preferably 2 to 8 wt %, more preferably 4 to 6 wt % of divinylbenzene, is appropriate to be used as a substrate for making the adsorbent for waste water which contains dye, heavy metal ion, surfactant, humic substance and etc.
Also, the present inventors have found that the polystyrene spherical resin of which size is 100 to 500 mesh, preferably 200 to 400 mesh, is desirable to be used as a substrate for making the adsorbent for waste water which contains dye, heavy metal ion, surfactant humic substance and etc.
In addition, the present inventor have further researched several methods for introducing xcex2 hydroxy group on the surface of polystyrene spherical resin without using propylene oxide or ethylene oxide(as to the method for introducing xcex2 hydroxy group on the surface of polystyrene spherical resin by using propylene oxide or ethylene oxide, please refer the present inventor""s U.S. Pat. No. 5,466,758).
Through the above research project, the present inventor have found out that xcex2 hydroxy group can also be introduced on the surface of polystyrene spherical resin by reacting polystyrene directly with 2-methyltetrahydrofuran, or by hydrolysis chloromethylpolystyrene with metal hydroxide, or by aminolysis chloromethylpolystyrene with ethanol amine or diethanol amine. Polystyrene spherical resin of the present invention, which is having a hydroxy group, may also be used as a intermediate material for making the polystyrene spherical resin grafted with polystyrene glycol.
Further, the present inventor have studied the proper content and proper molecular weight of polyethylene glycol of the polystyrene-g-polyethylene glycol adsorbent which has proper adsorption capacity and efficiency to be used as an adsorbent for waste water which contains dye, heavy metal ion, surfactant and etc.
As a result, the present inventor have found that the appropriate content of polyethylene glycol of the polystyrene-g-polyethylene glycol spherical resin to be used as a adsorbent, is more than 50 wt %, preferably 60 to 95 wt % in case that the polystyrene core is crosslinked with 1 wt % of divinylbenzen, and is 70 to 90 wt % in case that the polystyrene core is cross linked with 2 to 3 wt % of divinylbenzene.
Moreover, the present inventor have found that, for the purpose of using the polystyrene-g-polyethylene glycol spherical resin as the adsorbent which has best adsorption capacity and efficiency against dye, heavy metal ion, surfactant, humic substance contained in waste water or trash sediment water, it is desirable that the molecular weight of polyethylene glycol part of the polystyrene-g-polyethylene glycol is more than 500 Da, preferably more than 900 Da, most preferably 900 to 3,000 Da.
Therefore, it is an object of the present invention to provide a polystyrene spherical resin grafted with polyethylene glycol characterized in that polystyrene resin is crosslinked with 1 to 10 wt % of divinylbenzene, the content of polyethylene glycol is more than 50 wt % and the molecular weight of polyethylene glycol part, is more than 500 Da.
Another object of the present invention is to provide a process for decontamination of dye, surfactant, heavy metal ion, humic substance contained in waste water or trash sediment water by using the polystyrene spherical resin grafted with polyethylene glycol.
Still another object of the present invention is to provide a process for recovering dye by using organic solvent from a polystyrene spherical resin grafted with polyethylene glycol, whereon dye is adsorbed.
Still further object of the present invention is to provide a process for recovering a polystyrene spherical resin adsorbent grafted with polyethylene glycol through a elutriate process by using organic solvent.